Formulated and executed at the level of genetic analysis, this project centers on developing a unified molecular mechanism that will account for all aspects of meiotic recombination in yeast. From methodological and programmatic viewpoints, the project centers on the characterization of correction deficient (cor) mutants, and the identification and analysis of other principal loci that influence formation and repair of heteroduplex DNA. Additionally, we are engaged in a comprehensive study of the ways in which autonomously replicating plasmid vectors, respectively carrying DNA inserts containing the wild type loci for arg4 and ade8+, are integrated into the disassociated from the normal yeast genome. arg4 and ade8 are among the most thoroughly understood loci in the test system. Numerous alleles have been identified and these include specific mutants distinguished by high basic conversion frequencies and equally high PMS frequencies. Such mutants will be studied exhaustively. Finally, we plan to study the interactions between cloned centromeres and mutants that affect chromosome disjunction. These mutants are identified by novel screening methods developed in this laboratory. The mutants affect meiotic disjunction and chromosome gain rather than loss is monitored. Their complete characterization and analysis is projected. In effect, we shall exploit and apply the existing strategies and technologies generated from the study of recombinant DNA to the investigation of meiotic recombination in Saccharomyces cerevisiae.